How to Convert Foot-Candle Measurement

A foot-candle is a measurement of light intensity. This is a
non SI unit, but it can be easily converted into more useful units of
measure if you prefer including Lumens and Watts. By knowing a few
simple calculations, it should be much easier to work out exactly what
the foot-candle measurement really means.

If your light meter only calculates readings in food-candles, then
all is not lost because you should be able to easily work out what this
means in different units. The calculations are actually fairly easy to
understand and use.

Step 1: Measuring the Light Intensity

The first thing that you need to do is use your light meter to
measure the number of foot-candles that there are hitting the subject.
Once you have this number, you can then use it to convert it into Lumens
or Watts depending on what you want to do. For the case of this
example, we will base our calculations on a measurement of 50
foot-candles.

Step 2: Converting to Lumens

One foot-candle is equal to 10.76 Lumens. This means that you need to
take your foot-candles measurement and multiply it by 10.76. Using our
measurement of 50 foot-candles, we get the following equation: 50 x
10.76. By working out this calculation, you will be able to get 538
lumens. A lumen is the same as Lux and is what many modern light meters
will calculate their measurement in.

It's a good idea to write the measurement in Lux down because it's
very easy to forget no matter how easy it seems to be to remember it.

Step 3: Converting into Watts

The next thing that you can do is to calculate the number of watts.
This is very easy to do once you have converted into watts. One lumen is
equal to 0.001496 watts. This means that you simply need to take your
answer to step 2 and multiply it by 0.001496. In our example, 538 x
0.001496 equals 0.805 watts per square meter. Write this down again, and
you can use it to work out anything you want to know.

Step 4: Doing your own Calculations

Now that you know how to convert foot-candles to lumens (Lux) and
Watts. it is easy to do the same for your own measurements. Simply
substitute 50 for your own measurements.

To work out Lumens or Lux use the following Equation: Lumens = Foot-Candles x 10.76

To work out Watts use the following equations: Watts = Lumens x 0.001496

You can also calculate the number of watts directly from the
foot-candles by combining both equations and using the following: Watts =
Foot Candles x 0.01609696 This is because 10.76 x 0.001496 =
0.01609696).

Calculating and converting is very easy and shouldn't take very long
to do once you get used to it. As the number of lumens is just over 10 x
foot candles, it's also very easy to estimate the lumens calculations
in your head.